摘要:

AbstractOver the past 20 years Soviet research in regeneration has undergone a shift in emphasis from work on amphibians to mammals. In that period several distinct schools of thought have arisen, and often there has been considerable controversy as to the nature of certain regenerative processes. At present most mammalian tissues and organs are being studied with respect to natural regenerative capacity and means of stimulating further regeneration. The most striking results have been obtained in the areas of muscle and bone regeneration. Progress in other areas has been less spectacular. Considerable effort has been put into devising means of regenerating functional tissue from pathologically changed or irradiated organs. The field of regeneration research in the Soviet Union is quite highly organized and includes a relatively large number of workers. Progress has, to some extent, been impeded by shortages of equipment and biochemical preparations.

ISSN:0003-276X    

DOI:10.1002/ar.1091600402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1968

数据来源: WILEY

摘要:

AbstractCells with elongated nuclei resembling those of fibroblasts and/or Schwann cells had been noted previously in x‐irradiated portions of rat spinal cords. The present experiment was undertaken to determine the identity and fates of these cells. For this experiment, a 5 mm length of lumbosacral spinal cord was irradiated (4000 R) in three‐day‐old Holtzman rats. Groups of these rats and their litter mate controls were killed at intervals from 11 through 60 days following irradiation. Most of the spinal cords were prepared for light microscopic examination; a few were prepared for ultrastructural studies. Light microscopic examination revealed that the cells in question became observable near the dorsal roots within and immediately caudal to the irradiated area in a few rats as early as 15 days post‐irradiation and in all rats by 19 days following irradiation. The number of cells increased rapidly and in some cases filled the dorsal funiculi. Axons that were intermingled with these cells usually became myelinated approximately 25 days post‐irradiation. The myelin that formed on these axons resembled peripheral rather than central myelin. Reticular fibers were also abundant in the cell aggregations. The ultrastructural studies confirmed these observations. The data indicate that these cells were involved in formation of peripheral‐like nervous tissue within the spinal cord of all irra

ISSN:0003-276X    

DOI:10.1002/ar.1091600403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1968

数据来源: WILEY

摘要:

AbstractSome general statements concerning the overall geometry of the cerebellar vermis are presented as a preliminary step in the theoretical analysis of its morphology. From a large number of measurements made on a sample of 30 human cerebella the following relationships may be demonstrated: (1) the mean outline of superimposed sagittal sections through the mid‐vermis fits very closely the curve\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm r} = {\rm a\, sin}\frac{\theta }{2}; $$\end{document}(2) the relation of the total circumference (y) of individual lobes or of the entire vermis to a measurement of the outside (visible) perimeter (x) is shown to be fitted almost exactly by the equation y = ax2; (3) the relation of total circumference to outside perimeter in the rat and the cat is found to be constant during development; (4) in the human arbor vitae the relation of the width of the “trunk” to the sum of the widths of bifurcating branches is seen to be linear with a slope, in the midline, of approximately one; (5) no simple relationship could be ascertained in teh arbor vitae between angles of branching and widths of branches or t

ISSN:0003-276X    

DOI:10.1002/ar.1091600404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1968

数据来源: WILEY

摘要:

AbstractCertain modifications and clarifications of current concepts of the fine structure of the carotid body are described. The two principal cell types are here designated “enclosing” and “enclosed” to emphasize the enveloping nature of the former. The enclosed cells have numerous processes, contain lysosome‐like bodies which are sometimes related to crystals with a period of about 100Å. In addition to the typical dark‐cored vesicles, a few with lighter content are always present. The enclosing cells are in most respects similar in their contents to the enclosed, even to the presence of occasional dark‐cored vesicles. The fenestrations of the blood vessels apparently are closed by thin diaphragms.In addition to the type of nerve endings previously described, there is a second type which extensively surrounds the enclosed cells, in the manner of a basket, and differs from the first type in having relatively empty cytoplasm with few synaptic vesicles or mitochondria. It is postulated that this is the afferent ending, while the former may be efferent.Severe anoxia rendered both cell types more dense than normal. In contrast to previous reports, the dark‐cored vesicles of the enclosed cells did not disappear but rather increased in relative number, and their mitochondria were less opaque. No comparable changes were noted in control anoxic tissues of liver, kidney or adrenal medulla. The possibility is discussed that the enclosing cell has more than a simple supportive function, as the usual name “sustentacul

ISSN:0003-276X    

DOI:10.1002/ar.1091600405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1968

数据来源: WILEY

摘要:

AbstractTrigeminal ganglia were unilaterally macerated manually through the foramen ovale in three forgs.Rana catesbeiana, and in two toads,Bufo marinus. Following a two to three week post‐operative survival, each animal was anesthetized and was systemically perfused with formalin. Serial transverse frozen sections, 50 μ in diameter, were then prepared from the CNS of each animal. Selected tissue sections were stained according to a uranyl nitrate modification of the Nauta silver technique. The distribution of degenerating fibers was subsequently assesed by microscopic analysis.Degenerating trigeminal fibers could be traced from the trigeminal root into the vicinity of the chief sensory nucleus of the trigeminus and into the spinal V tract and nucleus in both toad and frog. The spinal V tract passed into the cervical spinal cord in all animals but did not pass further caudally than the third spinal segment. In some animals, degenerating fibers passed into the fasciculus solitarius and the nucleus solitarius. No trigeminal primary afferent fibers could be followed into the cerebellum or into the immediate vicinity of any of the cranial motor nuclei, in cluding the trigeminal motor nucleus. The distribution of Gasserian ganglion collaterals recorded in this study is discussed with reference to previous findings in the trigeminal systems of amphibians, birds and mamma

ISSN:0003-276X    

DOI:10.1002/ar.1091600406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1968

数据来源: WILEY

摘要:

AbstractA considerable area of the floor of the fourth ventricle, extending from the facial colliculus down to the vagal triangle, is underlaid by the nerve cells of the nucleus intercalatus. Only a minor portion of this nuclear complex is actually “intercalated” this portion comprising about 2,500 cells or 6% of the total. The great majority of cells making up this nucleus, 80% or 32,000 are found in front of the oral pole of the hypoglossal nucleus. The remaining 14% of cells or about 6,000 form a third distinct group located opposite the medial vestibular nucleus. The mean cell sizes in the three parts of the nucleus are also different, they are 90 μ2, 135 μ2and 190 μ2respectively. These differences of cell sizes and of location were the basis for the division of this nucleus into three parts by some authors. In the three cases studied, this division was, however, not so complete as to permit a separate cell count for each part to be kept. The mean of the cell frequencies in the three cases is 36349 ± 411

ISSN:0003-276X    

DOI:10.1002/ar.1091600407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1968

数据来源: WILEY

摘要:

AbstractA histochemical study was made of the nitrocatechol sulfatase activity in the rat placenta and metrial gland by the lead salt technique. Marked deposits of reaction product were demonstrated in the uterine epithelium and the granulated metrial gland cells. Diffuse reactions occurred in the visceral endoderm of the yolk sac and the trophoblastic gint cells in material fixed overnight, but with fixation in formalin for seven days these were replaced by discrete granular deposits. The reactions appear to be due to type II sulfatases. They have a distribution similar to that of β‐glucuronidase and organophosphate‐resistant esterase, except that the metrial gland cell sulfatase activity becomes reduced in late gestation and the early postpartum period. The postcoupling method with 6‐benzol‐2‐naphthyl sulfate, which demonstrates mainly sulfatase C, gives a differing distribution from the lead salt technique, and the reaction is almost completely abolished by prolonged formali

ISSN:0003-276X    

DOI:10.1002/ar.1091600408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1968

数据来源: WILEY

摘要:

AbstractA colony of adult rats was maintained on a standardized regimen with artifical photoperiods extending from 0600 to 1800 alternating with 12 hours of darkness. Every hour during a 24‐hour period separate subgroups of rats were injected with 35 mg/kg of pentobarbital sodium, and the duration of time each animal remained under anesthesia was recorded.The rats remained anesthetized for longer periods of time between the hours of 1600 and 2200 than at other times of the day; this indicates that the response to the drug is dependent on he circadian phase system of the animal. When the results were plotted along the 24‐hour time scale, the difference between the crest and trough of the curve was about 100%.A second colony of rats was maintained in a similar fashion except that the animals were subjected to continuous illumination. The rhythm of their susceptibility to pentobarbital sodium persisted for at least four weeks in a form highly modified from the animals synchronized to a light‐dark cycle.In a third colony of animals, the rhythm still was present four months after they had been blinded; but it was modified and different from either the light‐dark synchronized animals or from rats subjected to continuous illumination.The importance of recognizing the time structure of the living organism is di

ISSN:0003-276X    

DOI:10.1002/ar.1091600409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1968

数据来源: WILEY

摘要:

AbstractFetal membranes grafted to the omentum in mice do not degenerate at a time corresponding to the normal termination of the donor pregnancy, as would be expected if a “biological clock” were matching their lifespan with that of the embryo and placenta. Neither, in our experience, did such grafted membranes form a variety of highly differentiated secondary tissues, as some authors have suggested. Rather, the fate of the various components of the membrane seemed different for each cell type. In allogeneic hosts a brisk cellular reaction occurred and the membranes were destroyed. In isogeneic hosts, the grafts was vascularized and healthy membrane‐derived structures were still present after 33 days of grafting (48 days conceptual age). Mesothelial cells remained applied to well‐preserved basement membrane, whereas visceral endoderm cells appeared to degenerate or else detach themselves and become free rounded cells with foamy cytoplasm, sometimes multinucleated. Mesodermal cells accompanying the blood vessels of the membrane probably accounted for the connective tissue stroma seen in these grafts. The normal failure of the fetal membranes to persistin situafter the termination of pregnancy may result from the resistance of the uterine lumen to grafts not having highly invasive properties, together with the general sloughing of the uterine lining which takes place after d

ISSN:0003-276X    

DOI:10.1002/ar.1091600410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1968

数据来源: WILEY

摘要:

AbstractMice of the RF and C57 black strains, fed an adequate diet, were donors and recipients of subcutaneous tissue implants. Abundant ceroid formed in implants of liver, heart, and adrenal. The pigment developed concurrently with degenerative changes in hepatocytes and myocardial fibers. Ceroid was intracellular in implants of adrenal gland and limited to cortical cells. Skeletal muscle and multilocular fat cells were next most productive sources of ceroid. Unilocular fat cells produced only traces. Isogeneic and allogeneic implants of corresponding tissues revealed comparable amounts of ceroid after two weeks of transplantation. Formation of pigment was correlated with the type of tissue transplanted rather than to specific host‐graft responses.Implants of liver tissue were an ideal model for studying genesis of ceroid pigment. Granules of ceroid appeared first at the periphery of the implant in tissue adjacent to obviously degenerating cells of the graft. These small granules of pigment were then engulfed by macrophages. In most instances liposis preceded formation of ceroid. The presence of large amounts of lipid in the tissue at time of implantation did not augment ceroid formation. Hyper‐ and hypovitaminosis E, choline deficiency (to produce fatty livers), hyperestrogenism, and the administration of immunosuppressive drugs to recipients failed to influence appreciably the production of ceroid. In livers and other tissues containing little fat a relatively rapid post‐implantation liposis preceded ceroid form

ISSN:0003-276X    

DOI:10.1002/ar.1091600411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1968

数据来源: WILEY